Atmospheric Carbon Dioxide Concentration over Time

D ATMOSPHERIC CARBON DIOXIDE CONCENTRATION OVER TIME 

This correlation suggests, but does not prove, that the high concentration of carbon dioxide is the cause of the temperature increase. It is theoretically possible, but thought to be less likely, that other phenomena led to higher temperatures which, in turn, caused the carbon dioxide concentration to rise. However, carbon dioxide is known to trap heat so it is incumbent on us to see if the increasing concentration of carbon dioxide in our atmosphere and the resultant temperature increase in the past two hundred years, a mere blip in time on Eigure 6.1, are related to human activity. 

The movie Apollo 13 (released in 1995) is based on the real story of the ill-fated Apollo 13 moon mission of 1970. The most dramatic scene in the movie Apollo 13 combines carbon dioxide, inorganic chemistry, and human ingenuity. The three astronauts nearly died due to toxic levels of the carbon dioxide that they exhaled into the confined space of their lunar module. 

After two uneventful days on its way to the moon, an electrical short caused two of the oxygen tanks mounted on the outside of the command and space module to explode. In response, pilot Jack Swigert radioed Ground Control Houston, we ve had a problem here.  

To conserve energy, Ground Control ordered the three-man crew to shut down all electrical instruments, to move into the smaller Lunar Module, and to breathe as little as possible. Soon, however. Ground Gontrol realized that the CO2 scrubbers were also turned off and that GOg levels would build up unless something was done. During the process of respiration, COg and water are exhaled. 

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Atmospheric Carbon Dioxide Concentration Over Time... 

Atmospheric Carbon Dioxide Concentration over Time 127... 

Even if equilibrium had been achieved before the water mass sank, the observed water mass concentrations could exhibit apparent deviations from equilibrium, if the atmospheric pressures have changed or if the water mass temperature has been altered. Thus, deepwater that was last at the sea surface hundreds of years ago could potentially have equilibrated with the atmosphere at much different partial pressures of gases such as methane and carbon dioxide whose atmospheric levels have risen over time. For example, the partial pressure of CO2 in dry air has risen from about 280 ppm in the 1860s to 385 ppm in 2008. 

As a consequence of the realization that dissolution of magnesium- and calcium-containing sihcates controls carbon dioxide concentrations in the atmosphere over geologic time (e.g.. Equations (l)-(2)) and that such reactions may be important for subsurface carbon sequestration over human timescales, researchers have also become interested in the effect of dissolved inorganic carbon on dissolution. The indirect effect of CO2 species on dissolution of... 

Chemical transformation of carbon dioxide has attracted considerable interest because it presents possibilities of converting it into new chemical products and of reducing its concentration in the earths atmosphere [1]. In the chemical community, enormous efforts have been made to develop low-cost and catalyt-ically effective transition metal catalysts and reagents for the transformation of carbon dioxide [2]. Over the years, tremendous progresses have been made in understanding its reactions with various transition metal complexes [3]. At the same time, various interesting catalytic conversions of CO2 have also been discovered. 

There is abundant evidence for these alterations. Measmements of carbon dioxide concentrations in polar ice cores provide data relating to the last c. 420,000 years (Bamola et al., 2003) As ice accumulates, mini atmospheres are trapped in bubbles so the accmnulation of ice year on year generates an environmental archive with a record of the composition of air over time. Such work from the Antarctic and Arctic confirm that there are substantial differences between ice age (cold stage) and interglacial (warm stage) atmospheres, as shown in Figure 2.18. 

From Figure 9.1, it can be seen that the major form of carbon in the atmosphere is C02(g), constituting over 99% of atmospheric carbon. Carbon dioxide makes up 0.035% by volume of atmospheric gases, or 350 ixatm = 350 ppmv. The atmosphere has a mass of CO2 that is only 2% of the mass of total inorganic carbon in the ocean, and both of these carbon masses are small compared to the mass of carbon tied up in sediments and sedimentary rocks. Therefore, small changes in carbon masses in the ocean and sediment reservoirs can substantially alter the CO2 concentration of the atmosphere. Furthermore, there is presently 3 to 4 times more carbon stored on land in living plants and humus than resides in the atmosphere. A decrease in the size of the terrestrial organic carbon reservoir of only 0.1% y-1 would be equivalent to an increase in the annual respiration and decay carbon flux to the atmosphere of nearly 4%. If this carbon were stored in the atmosphere, atmospheric CO2 would increase by 0.4%, or about 1 ppmv y-l. The... 

The main use of buffers in the laboratory is in the preparation of solutions of known and constant pH. It is difficult to ensure that the pH of a solution is accurate simply by preparing an acid or alkali of a given concentration because, for instance, atmospheric gases such as carbon dioxide dissolve in them, and so the pH will vary slightly over a period of time. 

Carbon dioxide dissolved in water leads to the formation of carbonic acid and a consequent increase in H. Ponnamperuma (1967) has calculated that water at 25°C, in equilibrium with the normal concentration of CO2 in the earths s atmosphere (0.03% by volume), will attain a pH of 5.63. The weathering action of this weak acid over geologic time is well known to geologists (Krauskopf, 1967). Ponnamperuma s calculations also indicate that increased atmospheric CO2 concentrations will result in further decreases in pH, down to pH 3.97 with one amosphere of CO2. Respiratory CO2 concentrations in soil atmospheres can be 10 to 100 times greater than the normal 0.03% in the earth s atmosphere (Stotsky, 1972). Thus, pH values considerably lower than 5.63 can be achieved through respiration. Similarly, respiratory activity in shallow waters and tidal flats, especially at night when photosynthetic CO2 assimilation is halted, can cause a marked decrease in pH (Oppenheimer and Master, 1965). 

The ability of these compounds to absorb infrared radiation varies widely from compound to compound, as does their life in the atmosphere before they undergo photochemical reactions or are absorbed in the oceans or on land. Methane has a concentration of only l.Vppmv in the troposphere, which is much less than that of carbon dioxide. On the other hand, each molecule of methane has a global warming potential (GWP) value that is 21 times that of carbon dioxide over the course of 100 years. (Note the GWP value has been developed to compare the ability of each greenhouse gas to trap infrared radiation over 100 years relative to another gas by convention, carbon dioxide has a GWP of 1.) Although methane has a relatively short lifetime (a few years)... 

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